The tire tread compound is the most important compound in a tire that dictates wear, traction, and rolling resistance. It is a technical challenge to deliver excellent traction, low rolling resistance while providing good tread wear. The challenge lies in the trade-off between wet traction and rolling resistance/tread wear. Raising the compound Tg would provide good wet traction but, at the same time, increase the rolling resistance and tread wear. There are needs to develop a tread compound additive that can provide wet traction without lowering the rolling resistance and tread wear.
The common industrial practices in using tread compound additives to tailor the wet traction and rolling resistance independently is to apply one additive to improve the silica dispersion and rolling resistance without affecting the wet traction while using another additive to raise wet traction without modifying the rolling resistance. The functionalized SBR (styrene butadiene rubber) is one additive used to enhance silica filler dispersion in tread compounds and to reduce rolling resistance without affecting wet traction. Nanoprene™, sub-micron to micron sized gels from Lanxess with cross-linked butadiene cores and acrylic shells, is the other additive used to raise the wet traction without affecting rolling resistance. However, Nanoprene can only deliver limited improvement in wet traction. Additionally, the presence of gels inside the tread compounding by using Nanoprene could fundamentally degrade the mechanical performance of a tread compound, especially in fatigue and cut resistance. This invention provides a nano-micelle solution to the tread compounds with improved wet traction without affecting rolling resistance. With the fine dimensions of these micelles, fatigue and cut resistance of the tread compound is expected to be preserved.
Related references include U.S. 2012-0245293; U.S. 2012-0245300; U.S. Ser. No. 61/704,611 filed on Sep. 24, 2012; and U.S. Ser. No. 61/704,725 filed on Sep. 24, 2012.